Highly efficient organic photovoltaic cells with molybdenum oxide buffer layer

For improving the power conversion efficiency and fill factor of the organic photovoltaic cells (OPVs), molybdenum oxide (MoO₃) can be used as a buffer layer. In this study, we fabricated OPVs by inserting a thin and transparent molybdenum oxide (MoO₃) layer between the transparent indium tin oxide (ITO) and the organic photoactive layer, with the configuration of ITO/MoO₃ (10 nm)/poly(3-hexylthiophene) (P3HT) and [6,6]- phenyl C61 butyric acid methyl ester (PC₆₀BM)/lithium fluoride (LiF)/Al. By spin-coating, the device showed power conversion efficiencies as high as 4.2% under AM 1.5G (100mW/cm₂), enhanced fill factor of 0.67, a short circuit current density (Jsc) of 9.32 mA/cm₂, and open-circuit voltage (Voc) of 0.67 V. In the case of flexible OPVs, device with 10-μm-thick MoO₃ buffer or 45-μm-thick PEDOT:PSS buffer exhibited the power conversion efficiency (PCE) and fill factor (FF) of 1.54% and 0.44 or 0.76% and 0.30, respectively.